Step 6 Determine topographic factor K zt and apply factor to wall and roof

# Step 6 determine topographic factor k zt and apply

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Step 6: Determine topographic factor, K zt , and apply factor to wall and roof pressures, see Section 26.8 Step 7: Apply loads to walls and roofs simultaneously
Wind Loads (IBC Section 1609 & ACSE 7) ASCE Table 27.5-1
Wind Loads (IBC Section 1609 & ACSE 7) Example Find the wind loads for column line 2 if the fully enclosed rigid structure in Pittsburg, PA, shown in Figure 12.3 resists wind with column lines 1, 2, 3 and 4 Use Exposure Category B. The building is an office building.
Wind Loads (IBC Section 1609 & ACSE 7) Example 1. Risk Category II 2. From IBC Figures 1609.3(1-4), V = 115mph 3. Exposure Category B: (given) K Zt = 1 Exposure Classification – Enclosed (Given) 4. Enter table to determine net pressures on walls at top and base of building respectively, p h , p o , see Table 27.5-1 @ z = 65’: P h = 24.0psf, P o = 18.6psf 5. Enter table to determine net roof pressures, p z , see Table 27.5-2 @ z = 65’: p z = (0.756)-31.3 = -23.7psf
Wind Loads (IBC Section 1609 & ACSE 7) Example
Wind Loads (IBC Section 1609 & ACSE 7) Example 6. Determine topographic factor, K zt , and apply factor to wall and roof pressures, see Section 26.8 K Zt = 1, therefore no adjustments 7. Apply loads to walls and roofs simultaneously For Column Line 2, the tributary width = (26′ + 30′)/2 = 28′ w @ 65’ = 24.0psf(28’) = 672plf w @ 0’ = 18.6psf(28’) = 521plf @ z = 65′: tributary height = 7.5’ … p = 672plf(7.5’) = 5,040lb = 5.04k @ z = 20′: tributary height = 17.5’ … p = 521plf(17.5′) = 9,118lb = 9.12k
Earthquake Loads (IBC Section 1613 & ASCE 7) Regional in character Loading based upon several factors Weight of the building (Design Dead Loads) Design spectral response acceleration parameter Site coefficient Fundamental period of the structure Importance factor Based upon occupancy category given in IBC Table 1604.5 Occupancy category Seismic force-resisting system Response modification coefficient System overstrength factor Deflection amplification factor
Earthquake Loads (IBC Section 1613 & ASCE 7) Design Procedure Selection The structural analysis required by Chapter 12 shall consist of one of the types permitted in Table 12.6-1, based on the structure’s seismic design category, structural system, dynamic properties, and regularity, or with the approval of the authority having jurisdiction, an alternative generally accepted procedure is permitted to be used. The analysis procedure selected shall be completed in accordance with the requirements of the corresponding section referenced in Table 12.6-1.
Earthquake Loads (IBC Section 1613 & ASCE 7) Design Procedure Selection
Earthquake Loads (IBC Section 1613 & ASCE 7) Equivalent Lateral Force (ELF) Procedure Determine the Seismic Base Shear, V V = C s W Calculate the Seismic Response Coefficient, C s C s = S DS /(R/I e ) Where: S DS = the design spectral response acceleration parameter in the short period range as determined from Section 11.4.4 or 11.4.5 R = the response modification factor in Table 12.2-1 I e = the importance factor determined in accordance with Section 11.5.1 Determine the Effective Seismic Weight, W

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